A123Systems, a start-up in Watertown, Mass., says it has created a powerful, safe, long-lived battery.

General Motors selected A123Systems (along with its partner Cobasys) to develop batteries that might be used for its forthcoming plug-in hybrid Saturn Vue. It is considering awarding A123Systems a similar contract for the Volt, an extended-range electric concept car, to take advantage of the company’s new rechargeable lithium batteries.

“The real breakthrough is with the new batteries, which offered us energy density – which in turn provided us with a reliable, high-powered package in a relatively small space,” said Nick Zelenski, GM’s chief vehicle engineer.

Rechargeable lithium batteries have been used in laptop computers and mobile phones since the early 1990s. But despite their lightness, rechargeable lithium batteries have been thought impractical for transportation because they are insufficiently powerful and might, if pierced, jarred or overheated, explode.

A123Systems batteries are different.

The history of A123Systems offers a lesson in entrepreneurial adaptability. When Yet-Ming Chiang, a professor of materials science and engineering at MIT, and two others founded the company in 2002, they hoped to develop a technique where component materials would “self-assemble” into a practical lithium battery.

“Imagine sprayable batteries, conforming to the shape of a device or an appliance,” Chiang said.

But self-assembling batteries proved intractably hard to develop. So, in 2003, the company abandoned self-assembly for another technology. In place of cobalt oxide, it used a commonplace substance, iron phosphate, but assembled it in a novel nanostructure – the particles used were 100 times smaller than conventional oxides and 100 million times more conductive than conventional phosphates. The new combination offers high power, stability and longevity.